Modulated striking mechanism for electric alarm clocks



July 23, 1935. E. L. CARLSON El AL MODULATED STRIKING MECHANISM FORELECTRIC ALARM CLOCKS Filed Jul 28, 1932 Patented July 23, 1935 UNITEDSTATES PATENT OFFICE MODULATED STRIKING MECHANISM FOR ELECTRIC ALARMCLOCKS Application July 28, 1932, Serial No. 625,228

.5 Claims.

In electric'alarm clocks the motors of which comprise a rotor andastator magnet energized by alternating current, the hammers of the alarmsounding devices have, in some instances, been operated by the statormagnet by means of the magnetic impulses set up therein by thealternating current or by a supplemental magnet similarly energized. Insuch a mode of operation it has been found that the periodicity ofmovement of the hammer is so rapid that the sounding member respondsthereto with a buzz or whirr rather than the clear ringing tone desired.

The primary object of the present invention is to provide, in clocks ofthis type, an alarm sounding arrangement by means of which this faultmay be overcome.

To this end the invention consists in the provision of an alarm soundingmember and means of such construction and arrangement for striking samein response to the magnetic impulses set up in the magnet which operatessame that, although the magnet when energized by alternating current ofcommercial relatively high frequency, such as sixty-cycle, will impart avery rapid vibration to the striking means, the striking effect of sameupon the sounding member will be so modified or modulated as to producea clear ringing tone, all as will be explained hereinafter more fullyand finally claimed.

In the accompanying drawing illustrating the invention, in the severalfigures of which like parts are similarly designated,

Fig. 1 is a back view of those parts of an electric alarm clock in whichthe structure of the invention is embodied, a portion thereof beingbroken away in the interest of clearness;

Fig. 2 is a side view of the parts illustrated in Fig.

' Fig. 3 is a. bottom view thereof;

Fig. 4 is a perspective view of the hammer of the alarm mechanism;

Fig. 5 is a view similar to Fig. 4 but showing a modification; and

Fig. 6 is an enlarged axial sectional elevation of the alarm soundingmember and its mounting.

The clock, the motor and alarm sounding elements of which areillustrated in the drawing, is of the synchronous electric motor type,and

includes a suitable mounting plate I providingv bearings and supportsfor the rotor 2 and preferably laminated stator or field magnet 3 of theelectric motor which drives the time train of the clock (not shown) bymeans of an appropriate pinion or the like 4. The stator magnet 3 isprovided with coils 5, having terminals 6 attached to binding posts Iwhich form a means for connecting the motor with a suitable source ofalternating electric current through appropriate leads 8.

The back plate 9 (shown partially broken away in Fig. 1) which furnishesa protective covering or shield for the motor, and acts also as abracing means for. the laminated stator magnet 3, is preferably formedwith an integral support or bracket l0 having an offstanding portion Hto which the alarm sounding member or bell I2 is attached in a novelmanner presently to be described.

Although two forms of means for striking the alarm sounding member orhell 12 are shown in Figs. 1, 2, 3 and 4 and in Fig. 5, respectively,they are the same in the essential particulars whereby a clear ringingtone of the sounding member or bell I2 is obtained despite the rapidvibration imparted by the magnetic impulses set up in the operatingmagnet.

As shown in Figs. 1 to 4, inclusive, the striking mechanism comprises ahammer including a relatively rigid arm l3 so shaped as to form at oneend a bearing portion l4 and an apertured attaching lug 15, both ofwhich bear against the projecting end [6 of the stator magnet 3 andprovide a means whereby the arm may be fixedly attached thereto by anadjacent clamping bolt I! of the plurality of same which serve to securethe plates comprising the laminations of the stator magnet 3 in lamellararrangement. The arm I3 is provided intermediate its ends with an offsetportion Is by which it may clear the adjacent coil 5 and its oppositeend is is brought into proximity to the end portion 20 of the statormagnet 3 in position to be attracted thereby in response to magneticimpulses set up in the magnet as described.

Although the arm i3 is formed as a relatively rigid member, it hassuflicient inherent resiliency to permit it to vibrate relatively to thestator magnet 3 and sounding member or bell [2, its portion adjacent toits attached end l4 serving as a flexing hinge.

Instead of providing a striking part or clapper rigid with the end IQ ofthe arm l3, as has heretofore been done, a resilient member, preferablyin the form of a light spring leaf 2|, is riveted or otherwise rigidlyfixed at one of its ends at a point adjacent to the end IQ of the arm l3and carries at its other end a striker having a head 22 arrangedadjacent to one face of the end IQ of the arm l3 and a shank 23 by whichit is fastened to the member 2|, this shank extending through a recess24 in the end of the arm. By this arrangement of parts it will be seenthat the striker is resiliently mounted on the am l3 and is capable offree spring movement with respect thereto.

Instead of depending upon the flexing hinge action of the arm 53, asdescribed, the portion i i-l5 thereof may be joined to the offsetportion 58 by a hinge 25, Fig. 5, and the arm drawn to retractedposition by a helical or other spring 26 connected with it and with afixed part indicated at 27, a stop 28 being provided to limit the extentof its retraction.

It has been found, with a hammer thus constructed, that although thehammer advances to striking position and retreats therefrom insynchronism with the magnetic impulses set up in the stator magnet bythe alternating current, the provision of the resiliently mountedstriker, which is capable of striking movement relatively to thevibrating end H) of the arm, makes possible such desynchronization ormodulation of the striking action asto result in elimination of the buzzor whirr objected to and the production of the desired clear ringingtone.

Again referring to the mounting of the sounding member or bell l2hereinbefore mentioned, it has been found that the tone may be furtherimproved by cushioning this mounting. To this end the sounding member orbell I2 is provided with an aperture 29 in which is arranged acushioning member 33 of rubber or other relatively soft, yieldablematerial, preferably in the form of a grommet having portions 3iextending over and engaging the faces of the sounding member or bell I2,and provided with an axial opening 32 to receive a bolt 33 by means ofwhich the cushioning member may be compressed and the sounding member orbell I2 relatively rigidly attached to the portion I I of the bracket orsupport ID.

The bracket or support it has been described as formed integral with theplate 9, but, obviously, it could be made as a separate member, or thesounding member or bell could be otherwise suitably supported.

Although the alarm sounding member and its modulated striking mechanismare hereinbefore particularly described as adapted to an electric alarmclock the stator magnet of the motor of which is utilized to impartstriking movement to the hammer, it is to be understood that they may beincorporated in electric alarm clocks in which an auxiliary magnetenergized by alternating current and distinct from the stator magnet isemployed.

Various changes and modifications other than and in addition to thosespecifically referred to are considered to be within the spirit of theinvention and the scope of the following claims.

We claim:

1. An electric alarm clock comprising: an alarm-sounding member, amagnet having spaced poles and designed and adapted to be energized byalternatin current of commercial frequency to set up therein magneticimpulses, and a hammer for said sounding-member including arelatively-rigid magnetic arm rigidly secured to one pole and extendingto a second pole and having its end adjacent said second pole vibratablein synchronism with the alternating-current toward and away from saidsecond pole in response to the magnetic impulses set up in said magnet,and a striker resiliently mounted upon said magnetic arm and designedand adapted to vibrate relatively thereto and to strike saidsounding-member.

2. An electric alarm clock comprising: an alarm-sounding member, amagnet formed of laminations connected at spaced poles by bolts anddesigned and adapted to be energized by alternating current ofcommercial frequency to set up therein magnetic impulses, and a hammerfor said sounding-member including a relativelyrigid magnetic armmounted on one of said bolts at one of said poles and extending to asecond pole and having its end adjacent said second pole vibratabletoward and away from said second pole in response to the magneticimpulses set up in said magnet, and a striker mounted upon said magneticarm to strike said sounding-member.

3. An electric alarm clock comprising: an alarm-sounding member, amagnet having spaced poles and adapted to be energized by alternatingcurrent of commercial frequency to set up therein magnetic impulses, and.a hammer for said sounding-member including a relatively-rigid magneticarm rigidly secured to one pole and extending to a second pole andhaving its end adjacent said second pole vibratable toward and away fromsaid second pole in response to the magnetic impulses set up in saidmagnet, the movable end of said arm being provided with an aperture; aresilient member carried by said arm adjacent to its vibratable end andextending adjacent to said aperture; and a striker having a headarranged adjacent to one face of said arm and a shank extending throughsaid aperture and connected with said resilient member, said strikerbeing designed to have vibratory movement desynchronized relatively tothe vibratory movement of said arm and to strike said sounding-member inresponse to movement of said arm.

4. An electric alarm clock comprising: an alternating-current motorincluding a statormagnet formed of laminations connected at spaced polesby bolts and adapted to be energized by alternating current ofcommercial frequency; an alarmsounding member; and a hammer for saidsounding-member adapted to have striking movement imparted to it by thestatormagnet of said motor, said hammer including a relatively-rigidmagnetic arm mounted on one of said bolts at one of said poles andextending to a second pole and having its end adjacent said second polevibratable toward and away from said second pole in response to themagnetic im-' pulses set up in said stator-magnet, and a striker mountedupon said magnetic arm to strike said sounding-member.

5. An electric alarm clock comprising: an alternating-current motorincluding a statormagnet formed of laminations connected at spaced polesby bolts and adapted to be energized by alternating current ofcommercial frequency; an alarm-sounding member; and a hammer for saidsounding-member adapted to have striking movementimparted to it by thestator-magnet of said motor, said hammer including a relatively-rigidmagnetic arm mounted on one of said bolts at one of said poles andextending to a second pole and having its end adjacent said second polevibratable toward and away from said second pole in response to themagnetic impulses set up in said stator-magnet, and a striker mountedupon said magnetic arm to strike said sounding-member.

ELOF L. CARLSON. ARTHUR B. POOLE.

